We are studying the factors responsible for seeding microorganisms on the endothelium or the subendothelium of heart valves and vessel walls. The interaction of receptors on uninjured and injured endothelial cell layer with microorganisms that represent the most frequent offenders of the cardiovascular system (staphylococci, streptococci, candida) are being studied. Changes in the functional integrity of endothelial cells upon interaction with microbial agents will be determined. The role of blood platelets in these processes will be examined. A novel pharmacologic approach to this process will be assessed.